It is known in the art to synthesize speech using, generally, a speech synthesis processor and voice synthesis ROM. U.S. Pat. No. 3,998,045 issued to Lester discloses a timepiece that can be worn as part of a hearing aide or as a wristwatch that audibly announces time on demand using synthesized speech messages. In U.S. Pat. No. 4,279,030 issued to Masuzawa et al. discloses a speech-synthesizer timepiece that first produces an audible warning signal indicating that an audible speech message announcing time will follow and then produces the audible speech message representative of the updated time information. The advanced warning signal is provided to indicate that a voice message announcing updated time will follow. A time interval counter initiates the audible warning sound and a time delay provides for a pause between the warning sound and the voice message.
A voice annunciating system is disclosed in U.S. Pat. No. 3,641,496 issued to Slavin that has sensors that provide signals to control circuitry in response to specific detected conditions for selecting the proper synthesized speech message to be transmitted by the voice system identifying those conditions. The sensors detect conditions other than time although the control logic circuitry selects the appropriate speech message in response to the specific condition detected by the sensors.
Additional pertinent patents that show speech processing in response to either direct operator input to the speech processing circuitry or in response to updated time information provided by the timekeeping circuitry include U.S. Pat. No. 4,304,965 issued to Blanton et al., U.S. Pat. No. 4,287,584 Tanimoto et al. U.S. Pat. No. 4,060,848 issued to Hyatt, U.S. Pat. No. 4,016,540 issued to Hyatt, and U.S. Pat. No. 3,870,818 issued to Barton et al.,
However, as far as can be determined, no prior art timepiece has a battery backup to power a control computer when the main power supply, which provides power to the control computer and speech processing circuitry, fails. Furthermore, no existing timepiece produces a tone alarm when the speech processing circuitry is disabled during a main power supply failure and the timepiece being powered by a back-up battery.
An object of the invention is to continue to provide power to the talking timepiece circuitry during a power supply failure so that a functional tone alarm will be automatically provided by a computer controlled tone alarm generator even though the computer controlled speech processing circuitry is disabled.
Another object of this invention is to provide a timepiece having an optional and manually selectible means for announcing time by either speech synthesized messages or tone alarm sounds.
Another object of the invention is to bypass the manually selectible means during a power supply failure.
An additional object of the invention is to prevent incomplete speech messages when a subsequent speech message is requested.
A further object of the invention is to reduce the power dissipation in the main power supply.